Organopolysiloxanes containing aminoalkyl groups are employed as textile treatment agents, in the cosmetics industry and as release agents.
GB-A-20 36 052 describes organopolysiloxanes containing aminoalkyl groups which are formed when a polydimethylsiloxane containing terminal silanol groups and an alkoxysilane containing aminoalkyl groups are mixed at room temperature. However, the organopolysiloxane containing aminoalkyl groups prepared in this manner is cloudy since the alkanol formed as a condensation product and, optionally, water have limited solubility in the organopolysiloxane. On storage, further alkanol and water are formed during condensation reactions which proceed slowly, the siloxane chains are lengthened and an alkanol/water phase finally separates out. Accurate metering of the organopolysiloxane containing aminoalkyl groups is possible only after separation of the phases or emulsification thereof.
The separating out of alkanol and water can be avoided if the mixture is heated during preparation, in order to complete the reaction and at the same time drive off the alkanol and water. The removal in vacuo of the methanol formed in the reaction of silanols with methoxysilane containing aminoalkyl groups is described in G. Helary and G. Sauvet, Eur. Polym, J. Volume 28, No. 1 pages 37 to 41, 1991.